“Body-on-a-Chip”: A Microphysiological System for Drug DevelopmentMichael Shuler, Samuel B. Eckert Professor of Engineering, Cornell University, President & CEO, Hesperos, Inc., United States of America

Development of a human-based in vitro system has the potential to reduce dependency on animal testing and to make better predictions of human response to drugs. Also, there is the likelihood that by reducing the dependency on animals the process could be accelerated. In particular, in the event of pandemics or terrorism, the ability to use a human surrogate to rapidly screen possible drugs or candidate drug mixtures should be invaluable. Our efforts to construct human surrogates uses a combination of cell cultures and microfabrication. These devices have been referred to as "Body-On-a-Chip" systems. These devices are designed to be physical replicas of a physiologically based pharmacokinetic (PBPK) model where cell cultures or tissue engineered constructs are used to replace the differential equations for each organ compartment in the PBPK. A microfluidic system is used where each compartment is interconnect as they might be in a PBPK model. By using cell cultures in place of the equation, interactions of the drug with each tissue and communication between each tissue can be replicated even if the mechanisms are unknown and unexpected and would not be captured in the equation by themselves. Construction of a "pumpless" system is described and how might serve as a basis for a larger system (> 10 compartments) will be discussed. Such "chips" should be relatively low cost to construct and have the potential for broad application in drug development. I will discuss some of the issues in the design, construction and use of such devices.

09:45

On-chip Phenotypic Analysis of Inflammatory Monocytes in Atherogenesis and Myocardial InfarctionScott Simon, Professor of Biomedical Engineering, University of California-Davis, United States of America

Acute myocardial infarction (MI) associated with coronary artery disease affects more than 2.5 million Americans annually and is a major cause of mortality worldwide. While stable coronary artery disease (CAD) can be promptly diagnosed through stress testing and angiography, plaque rupture due to atherosclerosis remains highly unpredictable. Furthermore, studies have shown that 50% of patients with MI lack the traditional risk factors for CAD, including elevated low-density lipoprotein cholesterol, fasting triglycerides, hypertension, and diabetes. Therefore, there is a clinical need for non-invasive assays of inflammatory cell activation to gauge its role in atherogenesis. Based upon relative expression of the monocyte markers CD14 and CD16 we assessed their numbers with the onset of CAD. These were identified by flow cytometry and their numbers in circulation increased in high risk subjects postprandial following a high fat meal, and in MI patients before treatment. In these high risk and CAD cohorts, we examined adhesion molecule expression on monocyte subsets and found that a member of the€ß2-integrin family associated with atherosclerosis, CD11c/CD18, was upregulated 60% on CD14++CD16+ inflammatory subset of monocytes. Furthermore, CD11c was upregulated 300% on patients undergoing an MI compared to healthy subjects. Since the integrins CD11c and VLA-4 support monocyte recruitment on VCAM-1, we sheared subject’s whole blood in our vascular mimetic microfluidic flow channels over recombinant VCAM-1. We detected a ~25% increase in enrichment of CD14++CD16+ monocytes postprandial and an ~80% increase for MI patients. There was no significant enrichment of the other monocyte subsets. This lecture will describe a lab on a chip approach to define the respective roles of CD11c as a biomarker of CAD and activator of VLA-4 dependent adhesion on VCAM-1 in high risk subjects and those experiencing MI.

10:15

High-Performance Biomarker Analysis Using Microfluidic TechnologyYong Zeng, Assistant Professor, University of Kansas, United States of America

Microfluidics has emerged as a new paradigm in quantitative measurements of biomolecules and dynamic pathways across radically different spatiotemporal scales. In this presentation, I will share our research on developing microfluidics-based biotechnologies for quantitative analysis of cancer biomarkers, including bead-based digital PCR, actuatable microwell-patterned ELISA, and integrated microvesicle capture and analysis microsystem. Their applications to biomedical analyses of genetic mutations, protein biomarkers, and circulating exosomes derived from cancer patients will be discussed.

Microdialysis probes are an FDA approved way of sampling the molecular composition of human tissue including the brain, the low volume flow rates (0.2 – 2 µL / min) of microdialysis probes are ideal for linking to microfluidic analysis devices. Concentrations of key biomarker molecules can then be determined continuously using either electrochemically (using amperometric, and potentiometic sensors) or optically. Droplet-based microfluidics, by digitizing the dialysis stream into discrete low volume samples, (a) allows rapid concentration change to be detected without the effects of the temporal smearing caused by dispersion, and (b) allows dialysate droplets to be quickly transported from the patient or surgical field to the analysis chip. This talk will describe the design, optimization, calibration and use of both droplet-based and continuous flow microfluidic analysis systems for clinical monitoring during reconstructive surgery and, for traumatic brain injury patients, extended monitoring of the brain in the intensive care unit.

11:45

Keynote Presentation

Novel Strategies in Single Molecule SensingJoshua Edel, Professor, Imperial College London, United Kingdom

Analytical Sensors plays a crucial role in today’s highly demanding exploration and development of new detection strategies. Whether it be medicine, biochemistry, bioengineering, or analytical chemistry the goals are essentially the same: 1) improve sensitivity, 2) maximize throughput, 3) and reduce the instrumental footprint. In order to address these key challenges, the analytical community has borrowed technologies and design philosophies which has been used by the semiconductor industry over the past 20 years. By doing so, key technological advances have been made which include the miniaturization of sensors and signal processing components which allows for the efficient detection of nanoscale object. One can imagine that by decreasing the dimensions of a sensor to a scale similar to that of a nanoscale object, the ultimate in sensitivity can potentially be achieved - the detection of single molecules. This talk highlights novel strategies for the detection of single molecules using multiphase microfluidics.

Microfluidics is an enabling technology allowing miniaturization and integration of laboratory protocols into portable devices. In the past few years, largest diagnostic companies worldwide have adopted microfluidic technology to commercialize innovative diagnostic tests. First, this paper presents our last researches on the market of point of care technologies, including market trends and forecasts. Then, the presentation will focus on Point of Care microfluidic devices material and manufacturing trends. Does a standardization is expected in the coming years?

Session Title: Microfluidics/LOAC for Research Applications.

Session Chairs: Michael Shuler, Ph.D. and Carl Meinhart, Ph.D.

14:00

Next-Generation Proteomics ToolsAmy Herr, Associate Professor, University Of California Berkeley, United States of America

Technology advances have driven a genomics revolution with sweeping impact on our understanding of life processes. Nevertheless, the arguably more important “proteomics revolution” remains unrealized. Proteins are complex; meaning that multiple physicochemical properties must be assayed. Consequently, proteomic studies are resource intensive and ‘data limited’. To drive a bold transformation of biomedicine, engineering innovation in proteomics instrumentation is needed. While microfluidic technology has advanced separations science, progress lags in the multi-stage separations that are a hallmark of proteomics. This talk will summarize new microengineering design strategies for critical multi-stage protein assays. Specifically, I will introduce our tunable photopatterned materials for switchable function, microfluidic architectures for seamless integration of discrete stages, and multiplexed readouts for quantitation. In a translational example, I will detail assay and design advances from our highly integrated Western blotting platforms. Discussion will span the spectrum of demonstrated assays: from diagnostics for HIV confirmation to biomarker validation of protein isoforms to single cell level Western blotting in the context of stem cell differentiation. Performance and operational gains will be discussed, including quantitation capability, total assay automation, integration of sample preparation, and workflows that require minutes not days. Ultimately, we aim to infuse engineering advances into the biological and biomedical sciences.

The marriage of magnetic beads and microfluidics systems is an emerging trend for many applications. In addition to being magnetically responsive, magnetic beads offer a dramatic increase in surface area to volume ratio, and can be functionalized with variety molecules such as antibodies and enzymes. This talk will focus on the manipulation of magnetic beads using a droplet-based fluid handling technique called Digital Microfluidics (DMF) and its applications in sample preparation, immunoassays, and catalysis.

15:00

Coffee Break and Networking with Exhibitors in the Exhibit Hall

15:45

Technology Spotlight:Commercialization Strategies for Emerging Technologies in Digital Biology and DiagnosticsAli Tinazli, Vice President – Head of Business Development & Sales, Sony DADC US Inc

Greater than 20 million Americans are afflicted by over 80 clinically distinct auto-immune diseases, an immune system dysfunction in which the body attacks its own organs, tissues and cells. Systemic autoimmune diseases such as Systemic lupus erythematosus, Sjorgren syndrome and others are a specific subset of diseases tested via immunofluorescence anti-nuclear antibody (ANA) screens followed by a cascade of reflex tests to identify multiple sub-set markers. Testing with numerous standard IF or EIA assays exhibit many issues including interpretation differences in techniques as well as the sensitivity and specificity across the myriad of different vendor platforms and methods causing variability. The microarray platform is particularly well suited to profiling multiple markers because the numerous analytes are measured on a fixed platform within a single sample thereby reducing ambiguous measurements or erroneous interpretations. Here we describe a robust, low cost, high throughput method for screening multiple ANA reflex markers within a single sample well. Our method consists of recombinant antigen arrays printed on Grace Bio-Labs ONCYTE® porous nitrocellulose film slides and employs multiple quantum nano-particle (QNP) detection probes imaged with the ArrayCAM™ instrument. This platform provides high signal to noise measurements driven by the native protein orientation and high binding capacity of the ONCYTE PNC film substrate coupled with the spectrally distinct wavelengths of the QNP detector dyes and ArrayCAM reader. The advantages of this system over IF or EIA for a clinical laboratory include significant laboratory time savings, internal sample normalization, low cost instrumentation, familiar and easy to use protocols while providing sensitivity/specificity capabilities commensurate with clinical lab standards.

17:45

Separation-based Sensors for Monitoring Drug Metabolism and Neurotransmitters in Freely Roaming AnimalsSusan Lunte, Professor, University of Kansas, United States of America

Most behavioral studies using microdialysis sampling require tethering of the animal to the microdialysis system so that the animal is freely moving but not freely roaming. In this paper, we describe an on-animal separation-based sensor that combines microdialysis sampling with microchip electrophoresis. The goal is to develop a miniaturized device that can be placed on-animal and is capable of continuous monitoring of drug and neurotransmitter concentrations in the brains of freely roaming sheep. Such a device, combined with video recording, will make it possible to directly correlate neurochemistry with animal behaviour. Microchip electrophoresis is employed for the analysis since it makes possible the separation and detection of several analytes simultaneously with good temporal resolution. Analytes are detected using electrochemical detection, a mode particularly well-suited to such portable analysis systems since the electrode and the potentiostat are easily miniaturized. The current on-animal system is about the size of a lunch box and is run by a laptop battery. The instrument is remotely controlled using telemetry. This system was first demonstrated by monitoring the generation of nitric oxide from subcutaneous infusions of nitroglycerin in freely roaming sheep. Recent progress in the development of an on-animal sensor for the continuous monitoring of biogenic amines in brain microdialysis samples will be presented.

18:15

Cocktail Reception in the Exhibit Hall: Visit the Exhibitors and Network with Your Peers

Nanotextured Microfluidic Channels to Mimic Multiscale Architectures of Living TissueSamir Iqbal, Associate Professor of Electrical Engineering and Bioengineering, University Of Texas At Arlington, United States of America

Recent advancements in chip-based probing, detection and characterization of diseased cells provides new insights about disease development and interactions of sub-cellular species with the physiological environment. Our work on using microfabrication and nanotechnology towards new modalities to examine the presence or absence of particular disease biomarkers at molecular and cellular scale will be discussed. Some work done in my lab on the integration of biomedical engineering, nanoscience and nanotechnology, with particular focus towards their application in diverse areas like nanomanufacturing, molecular diagnostics, chip-based recognition of cancer cells and site-specific controlled drug delivery systems will be presented.

19:50

Microfluidic Devices with Drops/BubblesSung Kwon Cho, Associate Professor, University Of Pittsburgh, United States of America

Drops/bubbles provides unique functionalities in small scales and have spawn many novel microfluidic technologies, especially in digital microfluidics. In this talk, I will present and discuss a wide range of drop/bubble applications to microfluidic devices. The subtopics may include droplet-based particle sampling/concetrating/separating, bubble-based micro manipulators, and bubble-based micro propulsion for micro scale swimming robots. For these applications, the major actuating principles are electrowetting-on-dielectrics (EWOD) and acoustic excitation. Detailed mechanisms of these principles in the above applications will be also discussed in the talk.

Drug combinations have been increasingly applied in clinical treatments towards various types of lethal diseases, including HIV, TB and cancers, due to the superior advantages of high efficacy, low toxicity and low occurrence of drug resistance. The death rate of HIV patients was dropped by 60% in two years after drug cocktails were introduced. While the drug combinations are in generally effective, optimizing drug combinations remains challenging. M drugs with N dose levels lead to NM total possibilities. For instance, 6 drugs with 10 dose levels ends up 1 million combinations, a prohibitive searching space for conventional trial-by-error type of drug optimization approaches. Furthermore, drug-drug interactions and drug-system interactions can be extremely complicated. Therefore, the information acquired from individual cellular molecules could hardly assess the accumulative response at the bio-system level. Herein, we introduce a Feedback System Control (FSC) approach, aiming to rapidly optimize drug combinations out of millions of possibilities. The FSC approach combines biological experimental tests and engineering feedback control algorithms, avoids the high-throughput examination on large dataset, optimizes a few combinations iteratively, bypasses the complicated intracellular molecular interactions, and is able to identify the optimal solution with only several rounds of experiments by testing less than 0.1% of the total searching space. The FSC platform technology has been successfully applied for optimizing drug combinations for 3 types of viral infections, 6 types of cancers, and other biological scenarios such as paradise control, stem cell maintenance and optimization of traditional Chinese medicine (TCM).

Over the past century, electrical or electrochemical impedance spectroscopy (EIS) has been used by chemists and biologists to study reaction rate kinetics, corrosion phenomena, battery aging, and tissue characteristics to name a few applications. EIS measures a current or voltage response of a system to an alternating voltage or current signal and records the response as complex impedance. The key idea is that the input is a small amplitude signal and therefore permits use of small-signal theory and linearization to analyze system response through data containing both magnitude and phase information.

DNA microarrays have allowed extensive expression profiling of normal and pathological samples as well as whole-genome association studies aimed at finding the genes involved in frequent, multigenic diseases. While this has provided much new knowledge, the transition to actual clinical applications has been limited. Expression profiles have been applied for prognostic and predictive purposes, particularly in oncology and for breast cancer. Many tests (>50) have been proposed and published, but only a few are actually used and only one or two can be considered commercially successful. This is due to the need for a very robust implementation, to the required demonstration of analytical validity, clinical validity and above all clinical utility, in addition to regulatory requirements and cost/reimbursement issues. Whole-genome SNP profiling has revolutionised the genetics of complex diseases, with the successful implementation of GWAS studies that have at last provided solid identification of loci and genes influencing common, multigenic diseases. However the relative risks associated with the deleterious alleles identified are generally small, of the order of 1.2 to 1.5, and their predictive value at the level of an individual is accordingly very limited. Profiles marketed direct to consumers have met with regulatory problems. As additional knowledge accumulates in the future, these analyses will acquire more definite medical value.

We have developed prospective centrifugal microfluidic platforms, i.e. LabTube and LabDisk, and unleashed their potential for sample-to-answer point-of-care nucleic acid testing (POC NAT). The LabDisk platform consists of a disk containing the prestored reagents, and a handheld processing device. Several novel microfluidic unit operations, as required for POC NAT have been developed. These include magnetic bead handling, radially inward pumping, and cross-contamination free aliquoting. All unit operations are compatible with low-cost monolithic manufacturing, which will facilitate the market entry. On the other hand, the LabTube platform comprises a lab-on-a-chip cartridge that can be processed by a standard laboratory centrifuge. It obviates the need for highly specialized processing devices and may help to circumvent the known market entry barriers for lab-on-a-chip. These platforms have been demonstrated for sample-to-answer POC NAT using different sample matrices, such as whole blood, tissue, tumor cells and bacterial pathogens.

09:00

Free-Surface Microfluidics and SERS for High Performance Sample Capture and AnalysisCarl Meinhart, Professor, University of California-Santa Barbara, United States of America

Nearly all microfluidic devices to date consist of some type of fully-enclosed microfluidic channel. The concept of ‘free-surface’ microfluidics has been pioneered at UCSB during the past several years, where at least one surface of the microchannel is exposed to the surrounding air. Surface tension is a dominating force at the micron scale, which can be used to control effectively fluid motion. There are a number of distinct advantages to the free surface microfluidic architecture. For example, the free surface provides a highly effective mechanism for capturing certain low-density vapor molecules. This mechanism is a key component (in combination with surface-enhanced Raman spectroscopy, i.e. SERS) of a novel explosives vapor detection platform, which is capable of sub part-per-billion sensitivity with high specificity.

09:30

Keynote Presentation

Fabrication and Applications of Thermoplastic Nanochannels: Transport Behavior of Deoxynucleotide Monophosphates for Single-Molecule DNA SequencingSteve Soper, Foundation Distinguished Professor, Director, Center of BioModular Multi-scale System for Precision Medicine, Adjunct Professor, Ulsan National Institute of Science & Technology, William H. Pryor Emeritus Chair of Chemistry, The University of Kansas, United States of America

The major focus of this presentation will be to discuss new technologies, methodologies and fundamental knowledge in the area of single-molecule DNA sequencing using nanometer channels fabricated in thermoplastics. Nanochannels with dimensions <200 nm (width and depth) and lengths >50 µm are fabricated in polymer substrates using nanoimprint lithography (NIL) and resin stamps. The procedure basically involves using optical lithography and focused ion beam milling to make masters in silicon that consist of micro- and nanostructures. These masters are subsequently used to make resin stamps via UV-NIL. The resin stamps can then be used to make the required nanochannels in a variety of polymeric material, such as cyclic olefin copolymer, COC, and poly(methylmethacrylate), PMMA. Channels with dimensions to 15 nm (width x depth) and lengths to 100 µm have already been fabricated using this procedure. We will discuss the electrophoretic transport properties of deoxynucleotides monophosphates (dNMPs) through these channels that generate molecular-dependent flight times that can be used for their identification. The sequencing platform employs an exonuclease enzyme to produce the dNMPs from intact dsDNA molecules. Using fluorescence microscopy, we will show the single-molecule transport dynamics of dNMPs in a variety of nanochannel columns and compare results to the transport in microchannels. The electrophoretic migration behavior of the dNMPs using microchip electrophoresis was not possible unless cationic surfactants were added to the carrier electrolyte. However, due to transverse electromigation effects (TEM), different migration patterns of the dNMPs were observed in nanochannels. We will also discuss a host of surface modifications that can be invoked on the nanochannels to affect the surface charge density, topology and chemistry and the consequences of these modifications on the transport dynamics of dNMPs as well as the electroosmotic flow (EOF).

10:15

Coffee Break and Networking with Exhibitors in the Exhibit Hall

10:45

Plasmonic-Enhanced Single-Molecule DetectionSteve Blair, Professor, University of Utah, United States of America

The next generation of molecular diagnostics tools are targeted to have single molecule sensitivity. Plasmonic-enhanced fluorescence can be a key enabling factor in achieving this goal. Large-scale arrays of plasmonic structures meet the requirements of enhanced signal-to-background in fluorescence detection, along with compatibility with existing instrumentation and surface chemistry. Fluorescence enhancement results from a combination of plasmonic mediated excitation and emission enhancement. Even though molecules are confined within a plasmonic structure, the spectral region of enhancement depends strongly on the metal. As such, have also been working with structures in Al, which is mass-production friendly and provides balanced enhancement throughout the visible spectrum, opening up a wider range of applications. However, new chemical passivation strategies need to be devised due to the native oxide of Al. Tuning of the relative enhancements can be accomplished by adjusting the shape of the plasmonic structures, opening up the UV spectral range where the native fluorescence of biomolecules can be accessed.

11:15

NanoPlatform Embedded Reactions for Enhanced Chemical Transformations (NanoPERfECT)Paul Bohn, Arthur J. Schmitt Professor of Chemical and Biomolecular Engineering and Professor of Chemistry and Biochemistry, University of Notre Dame, United States of America

A foundational motivation for chemical sensing is that knowledge of the presence and level of a chemical agent can inform a decision about how that agent is to be treated, for example by sequestration, separation or chemical conversion to a less harmful substance. Commonly the sensing and treatment steps are separate. However, the disjoint detection/treatment approach is neither optimal, nor required. Thus, we are investigating how nano-architectures can be incorporated into microfluidic lab-on-a-chip devices so that molecular transport (analyte/reagent delivery), chemical sensing (optical or electrochemical) and subsequent treatment can all be coupled in the same physical space during the same translocation event. The last element of this triad, treatment, can be substantially enhanced if mass transport limitations can be overcome. In this context, in situ generation of reactive species within confined geometries, such as nanopores or nanochannels is of significant interest, because of its potential utility in overcoming mass transport limitations in chemical reactivity. The studies to be described focus on: (1) mass transport limited redox reactions to probe the coupling of electrochemical transformations to electrokinetic flow, and (2) solvent electrolysis for the generation of reactive species, such as H2. Semi-quantitative estimates of generation/consumption dynamics obtained from finite element modeling will be compared to quantitative nanoscale experiments. Collectively, we refer to these phenomena as NanoPlatform Embedded Reactions for Enhanced Chemical Transformations, or NanoPERfECT.

For many problems in system biology or pharmacology, in-vivo-like models of cell-cell interactions or organ functions are highly sought after. Conventional stationary cell culture in 2D plates quickly reaches its limitations with respect to an in-vivo like expression and function of individual cell types. Microfabrication technologies and microfluidics offer an attractive solution to these problems. The ability to generate flow as well as geometrical conditions for cell culture and manipulation close to the in-vivo situation allows for an improved design of experiments and the modeling of organ-like functionalities. In this paper we present a range of microfluidic devices designed for the co-culturing of a variety of cells, namely hepatic cells. The influence of substrate materials and surface chemistry on the cell morphology and viability for long-term cell culture has been investigated as well as strategies and medium supply for on-chip cell cultivation.

WEIDMANN Medical Technology AG separates itself from other microfluidic systems manufacturers in its ability to replicate micro- and nano-features in high volumes, while simultaneously integrating other technologies such as insert-molding (for metal parts, filter/paper parts and RFID), co-injection- (multicomponent) molding (hard-soft combinations, gasketing) and a high degree of automation for secondary operations such as bonding, surface treatments and packaging. Taken together, these capabilities can produce Lab-On-Chip systems of an amazing degree of complexity and integration while still being “disposable” in the classical economic sense. Turn-key solutions are our specialty.

Session Title: New Applications of Microfluidics and LOAC Devices.

Session Chairs: Henry White, Ph.D. and Paul Bohn, Ph.D.

14:00

Direct Separation and Analysis of Cells Mediated by Transient Molecular Interactions in Microfluidic DevicesRohit Karnik, Associate Professor, Massachusetts Institute Of Technology (MIT), United States of America

Multiple sample-processing steps present a challenge for the development of low-complexity devices for laboratory or point-of-care separation and analysis of cells. In this talk, I will discuss a new approach that can directly separate, enrich, or analyze cells with minimal or no sample processing requirements. We show that transient cell-surface adhesive molecular interactions can exert forces on the cells that can direct the trajectories of cells flowing through microfluidic devices. Such interactions occur in cell rolling, a physiological phenomenon involved in cell trafficking where transient molecular bonds are continuously formed and broken as the cell rolls on a surface under the action of hydrodynamic forces. Using this approach, we demonstrate separation of cells with high purity and efficiency in parallel microchannel devices, and direct separation of neutrophils from blood with ultrahigh enrichment in a neutrophil activation-dependent manner. We extend this approach to controllably contact mesenchymal stem cells with receptor-coated surfaces to quantify cell adhesion behavior by visualization of their trajectories in a “cell adhesion cytometer”, which can track changes in the cell phenotype. The results demonstrate the potential of the emerging technology of using transient cell-surface molecular interactions to directly separate and analyze cells for point-of-care diagnostics, isolation of rare cells, quality control of stem cells, and other applications.

14:30

Detection and Quantitative Analysis of Bacterial BiofilmsEdgar Goluch, Assistant Professor, Northeastern University, United States of America

Bacteria in nature typically exist as biofilms, complex microbial communities entrenched in a matrix of extracellular substances, not as free swimming individual cells. Biofilms are especially problematic because they protect and facilitate the survival of pathogens in hostile environments, leading to chronic and recurring infections. The Goluch Group investigates the chemical and physical micro-environments that bacterial cells respond to and create by developing and integrating sensing elements inside microfabricated fluidic systems. This talk will describe the development of electrochemical sensors for bacterial analysis and real-time detection of infections, and the use of surface plasmon resonance imaging (SPRi) as a tool for studying bacterial adhesion and removal.

15:00

Coffee Break and Networking in the Exhibit Hall

15:30

Application of the Latch Sensing Zone in a-Hemolysin for Analysis of ds-DNAHenry White, Professor, University of Utah, United States of America

Nanopores have been investigated as a simple and label-free tool to characterize DNA nucleotides when a ssDNA strand translocates through the constriction of the pore. Here, a wild-type a-hemolysin protein nanopore was used to monitor DNA repair enzyme activity based on base-specific interactions of dsDNA with the vestibule constriction “latch”, a previously unrecognized sensing zone in a-hemolysin specific for dsDNA structure. The presence of a single abasic site within dsDNA that is in proximity of the latch zone results in a large increase in ion channel current, allowing accurate quantitation of the kinetics of base repair reactions involving an abasic site product. Taking advantage of the high resolution for abasic site recognition, the rate of uracil-DNA glycosylase hydrolysis of the N-glycosidic bond, converting 2’-deoxyuridine in DNA to an abasic site, was continuously monitored by electrophoretically capturing reaction substrate or product dsDNA in the ion channel vestibule. Our results can be adapted to monitor the activity of other enzymes that introduce a change in the oligonucleotide structure, and thus provide a new approach for monitoring enzymatic activity on DNA. The discovery of a very sensitive sensing zone at the latch suggests the potential development of new methods to detect site-specific changes in dsDNA structure relevant to epigenetic, forensic and medical diagnostic applications.

In situ Probing of the Electrode-Electrolyte Interface via a Microfluidic Reactor Coupled with ToF-SIMSXiao Ying Yu, Senior Scientist, Pacific Northwest National Laboratory, United States of America

A portable vacuum interface allowing direct probing of the electrode-electrolyte interface was developed. This microfluidic electrochemical probe provides a new way to investigate the surface region and diffused layer with chemical speciation in liquids in situ by surface sensitive techniques.

16:30

Electrochemical Conversion of CO2 into Value added ChemicalsPaul Kenis, Professor, University of Illinois at Urbana-Champaign, United States of America

High levels of greenhouse gasses such as carbon dioxide have been identified as major contributors to climate change, which is starting to become evident, for example, in rising sea levels and erratic weather patterns. Multiple strategies, such as switching to renewable energy sources, improving the energy efficiency of buildings, and improving the energy efficiency of the transportation sector, will be needed to curb further increase of the atmospheric CO2 level. Another approach is the capture and subsequent electrochemical conversion of CO2 into useful chemicals such as formic acid, methanol, carbon monoxide, or short hydrocarbons. This presentation will cover our latest results in studying a range of catalysts (metal nanoparticles, organometallic compounds, metal-free systems), electrodes, and operating conditions (different electrolyte compositions), especially for the conversion of CO2 to CO, which is an intermediate for synthetic fuel production via the Fischer-Tropsch process.